This invention relates to gauges for measuring rain.
One class of rain gauges includes a transparent tube capable of holding water within it, having a floatable object inside of it and an open top to collect rain as the rain falls. Such rain gauges have marks extending vertically along the lateral surface of the transparent tube indicating the inches of rain and fractions of inches of rain so that as the floatable object rises, it indicates a mark showing the amount of rain that has fallen. Of course, units other than inches are used where appropriate such as millimeters or the like but inches will be referred to in this specification as an example.
A prior art rain gauge of this class has an opening which has the same diameter as the inner diameter of the tube. This inner diameter is constant throughout the height of the tube. The tube collects rain falling through a horizontal area equal to the cross-sectional area of the tube opening so that when an inch of rain has fallen the water in the tube rises one inch. Thus, the vertical marks indicating inches of rain spaced vertically along the tube are directly to scale.
This prior art type of rain gauge has a disadvantage in that it is difficult to read the scale along the vertical wall of the rain gauge because it is so small. Moreover, many rain gauges of this type are relatively complicated in construction and are expensive.